The present invention relates generally to the field of angular displacement motors and, more particularly, to an improved limited angular magnetically centering torque motor.
A variety of limited angle torque motors are known in the prior art which include an angular centering function when no torque producing currents are applied. In limited angle torque motors known in the prior art, this angular centering function is achieved by a separate passive magnetic centering mechanism attached to an extension of the motor shaft. However, such configurations result in greater complexity in the design of the motor.
Hence, it would be beneficial to have a torque motor in which the shaft has inherent angular centering characteristics unaided by an independent magnetic centering mechanism.
With parenthetical reference to the corresponding parts, portions or surfaces of the disclosed embodiment, merely for the purposes of illustration and not by way of limitation, the present invention provides an improved limited torque motor (15) having a magnetized rotor (16) mounted for rotational movement relative to a stator (18), the rotor and stator being elongated about an axis (x-x) and the stator having coils (19) adapted to be selectively energized by a current to exert a torque on the rotor.
The improvement comprises the stator having a centering magnetic configuration (20) at a first axial location (21) and arranged to produce a torque on the rotor as a function of rotor angular displacement (A), and the stator having a driving magnetic configuration (23) at a second axial location (24) and arranged to produce a torque on the rotor as a function of the current.
The stator may comprise multiple radial pole pieces (severally indicated at 35) and the coil may be wrapped around each of the pole pieces. The centering magnetic configuration may have less pole-pieces than the driving magnetic configuration. The rotor may have a constant magnetic configuration along its axis. The sum of the axial lengths of the centering configuration and driving configuration may be approximately equal to the axial length of the rotor. The stator may comprise a stack of laminated sections and certain of the laminated sections may be of the driving configuration (42) and certain of the laminated sections may be of the centering configuration (43).
Accordingly, the general object of the present invention is to provide an improved limited angular displacement motor with an inherent angular centering characteristic.
Another object is to provide an improved limited angular displacement motor which does not employ a separate magnet to produce a centering characteristic.
Another object is to provide an improved limited angular displacement motor in which the centering torque is a function of the angular displacement of the rotor.
Another object is to provide an improved limited angular displacement motor which produces torque as a function of current.
Another object is to provide an improved limited angular displacement motor in which the stator has both a centering magnetic configuration and a driving magnetic configuration.
Another object is to provide an improved limited angular displacement motor in which the centering configuration and driving configuration of the stator are approximately equal to the axial length of the rotor.
Another object is to provide an improved limited angular displacement motor in which the stator comprises laminated sections, certain of which provide a driving magnetic configuration and certain of which provide a centering magnetic configuration.
Another object is to provide an improved limited angular displacement motor having constant high torque at its operating current.
Another object is to provide an improved limited angular displacement motor in which the magnetic centering mechanism produces a part of the total driving torque of the motor.
These and other objects and advantages will become apparent from the foregoing and ongoing written specification, the drawings, and the appended claims.